Several modifications of the historical bow have been developed for the purpose of increasing the energy imparted through flexible spring arms when the bowstring is drawn. An early example of this is the device described in U.S. Pat. No. 2,116,650, issued May 10, 1938, in which flexible metal straps, attached to a central spring tension means, extend along the convex side of the flexible arms.
Other modifications have substituted hinged spring-controlled arms attached to the ends of the central rigid portion for the customary flexible spring arms. An early example of this is a device in U.S. Pat. No. 428,912, issued May 27, 1890.
With heavy hunting bows, it is possible to produce unequal tension on the ends of the bowstring with the drawing of the bowstring; or in other words, temporarily producing an unbalanced bow and influencing the accuracy imparted to the arrow. Thus, an important object of the present invention is to provide means which will insure equal tension being exerted at both ends of the bowstring as desired when the drawn bowstring is released.
U.S. Pat. No. 3,486,495, issued Dec. 30, 1969, describes an improved archery bow in which a pair of variable leverage elements on bow tips provide a mechanical advantage through which less force is required to hold the bowstring in fully drawn position than in an intermediate position. An object of the present invention is to achieve this same purpose in one of its embodiments with a simple construction and at the same time maintaining a balanced bow for accurate shooting.
Also, the two variable leverage elements on the bow tips of the bow shown in U.S. Pat. No. 3,486,495 must be coordinated to rotate in unison for accurate shooting of arrows. Such is difficult to accomplish. The present invention does not have variable leverage elements on the bow tips but instead uses a single control means to accomplish the same purpose so that no manual coordinating adjustment is needed to maintain a balanced bow.
Another object of the present invention is to provide adjustments for bowstring tension and draw length which are easy to accomplish.
Anther object is to provide novel control means which controls tension variations as the bowstring is drawn and further to provide adjustment in such control means to make the bow more versatile.
Another object is to provide in a bow embodiment using flexible bow arms a connecting flexible link between the arms that equally distributes the force of the two arms into one or a common tensioning means. This is an important factor. It is a further object to provide adjustment means in the flexible link to adjust tension thereof.
Still another object of this invention is to provide a bow which, while having more than one line between the arms, such as the bowstring and other lines, does not use any criss-crossing of the lines. Such criss-crossing of lines has the disadvantage of making the bow more likely to get snagged on brush. The cross-crossing of lines also presents the possibility of causing arrows shot from the bow to be deflected as they are shot.